SRSport Rules
Tennis - Singles court

Singles rules and court positioning, without the alley confusion.

Singles tennis is one player against one player, but the court still shows doubles lines, service boxes, center marks, and net-post details that can make simple calls look uncertain. The key is to separate the court used for singles rallies from the service box used to start each point.

Quick ruling: in singles, the singles sidelines and baselines define the rally court. The server must stand behind the baseline on the correct side and serve diagonally into the correct service box; after a legal serve, either player may move anywhere on their own side and, when playing a ball, may run outside the court lines if the ball remains in play.
Court boundaries

What counts as the singles court

  • The singles sidelines are the side boundaries: the doubles alleys are out during singles rallies unless a local court marking creates a different approved format.
  • The baselines close the court at each end: a shot landing beyond the baseline is out, while a shot touching the baseline is good.
  • The line is part of the court: if any part of the ball touches a relevant singles line, the ball is in.
  • The service boxes matter only for the serve: once the serve is legally in play, the ball can land anywhere inside the singles court.
Starting a point

Where the server and receiver stand

  1. The server stands behind the baseline, between the center mark and the correct singles sideline extension.
  2. The first point of a game is served from the right-hand court, also called the deuce court.
  3. The serve then alternates sides each point: right, left, right, left, through the game.
  4. The serve must pass over the net and land in the diagonally opposite service box.
  5. The receiver may stand where they choose on their own side, inside or outside the baseline, as long as they do not deliberately hinder the server.
The alley issue

Why doubles lines stay visible in singles

Most courts are painted for both singles and doubles. In a singles match, the wider doubles sidelines are not the rally boundaries. A groundstroke landing in the alley is out even if it would be in for doubles. The visible alley does not become playable just because it is marked on the court.

Service box

The serve uses a smaller target than the rally

A legal singles serve must land in the correct diagonal service box, not simply somewhere inside the singles court. A serve landing deep near the baseline, wide beyond the service sideline, or in the wrong service box is a fault. After the serve is good, normal singles boundaries apply for the rest of the rally.

Movement

Players may leave the court to play the ball

Singles positioning is not a requirement to stay inside the painted rectangle. A player may run beyond the sideline, behind the baseline, or around the net post area to reach a ball, provided they do not touch the net during play, invade the opponent's court illegally, or hit the ball before it has crossed to their side when the rules require it.

Changing ends

When players switch sides

Players change ends after the first game of each set and then after every odd-numbered game in that set. In a standard tiebreak, players also change ends after every six points. Some events use competition-specific formats, but the purpose is the same: neither player should keep the same wind, sun, or court-end advantage for too long.

Common mistakes

What singles positioning does not mean

  • The receiver does not have to stand behind the baseline: they may return from inside the court, well back, or outside the sideline extension.
  • The server cannot choose any baseline spot: before contact, the server's feet must stay within the legal serving area for that point.
  • A ball in the doubles alley is not good in singles: the relevant sideline is the singles sideline.
  • Crossing outside the court is not automatically illegal: the violation depends on contact with the net, illegal contact with the ball, hindrance, or entering the opponent's court in a way the rules prohibit.
Officials

How singles court calls are enforced

Officials identify the relevant line first: singles sideline, baseline, service line, center service line, or center mark. On a serve, they judge the server's position and the service box. During a rally, they judge whether the ball touched the singles court before any second bounce or other loss-of-point event. In unofficiated matches, players usually call balls on their own side and should give the opponent the benefit of doubt on uncertain line calls.